4.15-stable review patch. If anyone has any objections, please let me know.
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From: James Hogan jhogan@kernel.org
commit 6ae1756faddefd7494353380ee546dd38c2f97eb upstream.
MIPS' struct compat_flock doesn't match the 32-bit struct flock, as it has an extra short __unused before pad[4], which combined with alignment increases the size to 40 bytes compared with struct flock's 36 bytes.
Since commit 8c6657cb50cb ("Switch flock copyin/copyout primitives to copy_{from,to}_user()"), put_compat_flock() writes the full compat_flock struct to userland, which results in corruption of the userland word after the struct flock when running 32-bit userlands on 64-bit kernels.
This was observed to cause a bus error exception when starting Firefox on Debian 8 (Jessie).
Reported-by: Peter Mamonov pmamonov@gmail.com Signed-off-by: James Hogan jhogan@kernel.org Tested-by: Peter Mamonov pmamonov@gmail.com Cc: Ralf Baechle ralf@linux-mips.org Cc: Al Viro viro@zeniv.linux.org.uk Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org # 4.13+ Patchwork: https://patchwork.linux-mips.org/patch/18646/ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/mips/include/asm/compat.h | 1 - 1 file changed, 1 deletion(-)
--- a/arch/mips/include/asm/compat.h +++ b/arch/mips/include/asm/compat.h @@ -86,7 +86,6 @@ struct compat_flock { compat_off_t l_len; s32 l_sysid; compat_pid_t l_pid; - short __unused; s32 pad[4]; };